1. Field of the Invention
The invention relates to a rolling bearing device.
2. Description of Related Art
As a lubrication system for rolling bearing devices, grease lubrication has been widely used. In order to maintain lubrication performance even under severe lubrication conditions such as high temperatures, high-speed rotations, and high loads, a grease reservoir is provided in the outer ring spacer for a bearing and a base oil contained in grease reserved in the grease reservoir is supplied into the bearing. Rolling bearing devices having such a type of mechanism are described, for example, in WO 2010/010897 and Japanese Patent Application Publication No. 2005-180629 (JP 2005-180629 A).
WO 2010/010897 describes a rolling bearing device including an inner ring, an outer ring, a plurality of balls that serves as rolling elements interposed between the inner and outer rings, a cage that holds the plurality of balls at given intervals in the circumferential direction thereof, a seal that seals one end of the annular space between the inner and outer rings in the axial direction, and an annular grease reservoir member that has grease reserved therein and is provided so as to be close to an annular groove adjacent to the guide face of the outer ring that guides the rotation of the cage.
JP 2005-180629 A describes a rolling bearing including an inner ring, an outer ring, a plurality of rolling elements interposed between the raceway surfaces of the inner and outer rings, a grease reservoir formation part that is provided in contact with the outer ring, and a gap formation piece that provides communication between a grease reservoir and the vicinity of the raceway surface of the outer ring such that a gap is formed along the inside face of the outer ring.
When the rolling bearing device of a grease inclusion type is continuously used, a breakage (gap) may occur near the communication path between a grease reservoir and a bearing, as a base oil contained in grease in the grease reservoir is supplied. When the breakage extends over an entire periphery in a circumferential direction, the supply of the base oil to a rolling bearing is stopped although the grease remains in the grease reservoir. In case that the supply of the base oil is stopped, the lubrication performance for the bearing is lost when the base oil in the rolling bearing is completely consumed. Therefore, it becomes difficult to use the rolling bearing device over a long time period.
Meanwhile, JP 2005-180629 A describes a technique in which the base oil of the grease is supplied to a position near the raceway surface of the outer ring with the structure in which the minute gap is formed between the outer ring and the gap formation piece, in order to maintain lubrication performance for the bearing over a longer time period. However, in the technology described in JP 2005-180629 A, it is necessary to accurately design the shape of the gap formation piece to form the minute gap. Therefore, the structure may be complicated.